Setting tool

Abstract

A setting tool includes a sleeve-shaped housing (11), a piston guide (13) and an ignition unit (12) located in the housing (11), with the ignition unit (12) having a cartridge chamber bottom (19) for enclosing a propellant (25) in cartridge chamber (18), which is located between the piston guide (13) and the ignition unit (12) and a locking device (30) having a locking position (38) in which the ignition unit (12) is held in a pre-loaded position (28) against an energy accumulator (23) and in which the cartridge chamber (18) remains open, and having a release position (39) in which the ignition unit (12) is displaced to its ignition position (29) by the energy accumulator in which the cartridge chamber bottom (19) closes the cartridge chamber (18).

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a setting tool having a sleeve-shaped housing, a piston guide, a piston displaceable in the piston guide, an ignition unit located in the housing and axially displaceable therein, a cartridge chamber arranged between the piston guide and the ignition unit, with the ignition unit having a cartridge chamber bottom for enclosing a propellant in the cartridge chamber and an ignition element for igniting the propellant.[0003]2. Description of the Prior Art[0004]Setting tools of the type described above can be driven by solid fuels in powder form or pellet form. In this setting tool, the setting or drive piston is driven by combustion gases. With the setting piston, fastening elements are driven into constructional components. German Publication DE-19544105A1 discloses an explosive powder charge-operated setting tool in which a piston guide and an ignition unit with a displaceable ignition pin...

AI Technical Summary

Benefits of technology

[0007]A setting tool according to the present invention is characterized by a locking device or mechanism with which the ignition unit is held in a pre-loaded position against an energy accumulator in which the cartridge chamber remains open. Upon actuation of appropriate actuation means, the locking device releases the ignition unit which is displaced in its ignition position by the energy accumulator. The cartridge chamber bottom, which is carried by the ignition unit, closes the cartridge chamber, and the ignition element, which is also carried by the ignition unit, ignites the propellant enclosed in the cartridge chamber. The elements according to the present invention insure that the propellant remains in the cartridge chamber for a very short time and that the cartridge chamber, which becomes heated after a prolong use of the setting tool is held at a distance from the cartridge strip. The ignition unit is displaced into its ignition position after actuation of the ignition process very rapidly, so that the thermal conditions, which lead to an undesirable ignition of the propellant, are prevented.

[0008]In an ideal case, the ignition element, e.g., an ignition peg or pin is fixedly secured on the ignition unit and is displaceable therewith. This permits to initiate ignition of the propellant simultaneously with the closing of the cartridge chamber with the cartridge chamber bottom that is carried by the ignition unit. The present invention permits to eliminate a number of components and manufacturing processes during manufacturing of the setting tool, as there is no need in a separate, displaceable ignition pin.

[0009]The locking device according to the present invention can include at least one locking element, which can be formed, e.g., as a pivotally supported locking pawl. In the locking position of the locking device or the locking element, the pawl section of the locking pawl extends into the displacement path of the ignition unit, holding the ignition unit against a biasing force of the energy accumulator acting on the ignition unit. The locking pawl can be pivoted out of the displacement path of the ignition unit with a very simple mechanism, e.g., upon actuation of the actuation switch. Preferably, in an advantageous embodiment of the present invention, the locking element or the locking pawl is supported on a bearing axle supported on the housing, which permits to obtain a very robust constructions.

[0012]In an advantageous embodiment of the present invention, the setting tool is provided with a safety element, e.g., a catch pawl. The safety element extends, in its safety or locking position, into the displacement path of the ignition unit. With the safety element, the catch pawl, the ignition unit can be held back, upon opening of the cartridge chamber as a result of spring-back or recoil of the ignition unit, from impacting the cartridge chamber again. This advantageously prevents multi-ignition of the propellants located in the cartridge chamber during a setting process.

[0018]According to another advantageous embodiment of the present invention, the guide for the cartridge strip is secured at the front end of the ignition unit on its side facing the cartridge chamber and is displaceable with the ignition unit. With this arrangement of the cartridge strip guide, heat transmission from a heated cartridge chamber to the cartridge strip, in the inoperative position of the setting tool, is also prevented.

Problems solved by technology

The drawback of the known setting tool consists in that because of a comparatively long time the propellant is enclosed in the cartridge chamber, after a prolong operation of the setting tool, the propellant can self-ignite because of heating of the cartridge chamber.

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